title: Reliability of pulse oximetry in hypoxic newborn pigs.
abstract: OBJECTIVE
  The reliability of pulse oximetry in the lower SaO2-ranges has not been fully investigated. We wanted to investigate pulse oximeter performance in a pig model of perinatal asphyxia.
  
  
  METHODS
  Asphyxia was induced in 22 newborn pigs. Pulse oximetry-values for SpO2, as well as SaO2 from blood gas analyses were recorded multiple times before, during and after asphyxiation. The relationship between SpO2 and SaO2 in normoxia and hypoxia in this model was quantified. Calculations were made for 5% increments of SaO2 increasing successively from ≥95% to ≥20%.
  
  
  RESULTS
  The pigs became severely hypoxic, acidotic and hypotensive. The bias in the total data was +13.7 (p < 0.001), i.e. SpO2 was on average higher than SaO2 for the entire interval of SaO2. However, bias was not significantly different from zero in most SpO2-ranges. Accuracy and precision were considerably higher than stated by the manufacturer in all SpO2-ranges, with both accuracy and precision increasing when SpO2-values down to 60% and lower were included.
  
  
  CONCLUSIONS
  Pulse oximetry was less reliable at SaO2-values below 60%. Tissue acidosis and reduced peripheral perfusion may have contributed to this. It is unknown whether the difference between SpO2 and SaO2 is clinically relevant.
authors.affiliation: Department of Pediatric Research, Oslo University Hospital Rikshospitalet, University of Oslo , Oslo , Norway .
authors.forename: Anne Lee
authors.initials: AL
authors.lastname: Solevåg
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dannevig
authors.forename: Jūratė
authors.initials: J
authors.lastname: Šaltytė-Benth
authors.forename: Ola D
authors.initials: OD
authors.lastname: Saugstad
authors.forename: Britt
authors.initials: B
authors.lastname: Nakstad
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001237:Asphyxia / Q000097:blood; D001784:Blood Gas Analysis; D000860:Hypoxia / Q000097:blood; D010092:Oximetry / Q000379:methods / Q000592:standards / Q000706:statistics & numerical data; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results; D013552:Swine; D013997:Time Factors
chemical_list: D010100:Oxygen